Mechanism of Ta on the microstructure and properties of Fe-Mn damping alloys

Fe-Mn-Co-xTa alloys (x = 0, 1, 2, 3 wt.%) were fabricated using spark plasma sintering to explore the influence of Ta content on the microstructure, mechanical properties, and damping characteristics of Fe-17Mn-3Co damping alloys. The microstructural analysis reveals the dominant presence of gamma-austenite, epsilon-martensite, alpha '-martensite, and Co3Ta precipitates within the alloy. Incremental increments in Ta content exhibit proportional enhancements in hardness, tensile strength, and fracture elongation of the alloy. Notably, these improvements in mechanical attributes are closely correlated with the generated second-phase Co3Ta. As the Ta content increases, there is a gradual augmentation in the formation of Co3Ta within the alloy. Consequently, the damping property initially experiences an ascent followed by a subsequent decline with rising Ta content. This damping behavior finds its origins in multiple mechanisms, including grain boundary damping stemming from reduced grain size, interfacial damping induced by the generated Co3Ta, and dislocation damping. It is noteworthy that the emergence of the secondary phase wields a dual impact on damping property. On the one hand, the proliferation of the second phase fosters increased interfaces for energy dissipation. On the other hand, these interfaces give rise to compressive stresses, constraining interface movement and thus impeding damping property enhancement.